PT1891328E - Floating wind turbine installation - Google Patents

Description

DESCRIPTION " FLOATING WIND TURBINE INSTALLATION " The present invention relates to a floating wind turbine installation and a method for coordinating the hydrostatic and hydrodynamic properties of the wind turbine installation. The wind turbine installation comprises: a floating body; a tower arranged on the floating body; a generator housing which is mounted on the tower, which can rotate relative to the direction of the wind and which is equipped with a wind rotor; and a system of anchor moorings attached to the anchors or anchoring points on the seabed. The development of anchored floating wind turbines that can be used at great depths will significantly increase access to areas for the expansion of offshore wind power. The current technology for wind turbines located at sea is limited to permanently installed towers at low depths below approx. 30 m.

Permanent installations at depths of 30 m depth usually give rise to technical problems and high costs. This means that up to now, sea depths of over 30 m have been considered technically and commercially unfavorable for the installation of wind turbines.

With floating solutions at greater sea depths, the problem of foundations and the costs associated with complicated and labor-intensive installations can be achieved.

In this context a great deal of work is being done to develop floating solutions. However, it is difficult to find solutions that are technically satisfactory and financially viable. GB 2378679 discloses a floating dewatering structure comprising a watertight hull, a gravity or suction foundation comprising one or more components on the seabed and one or more floating devices connected to said watertight hull and configured to provide more buoyancy and more stability. Dade. US 6431107 discloses an offshore flow structure, i.e. offshore, with a watertight shell and a flexible stretcher connected between the hull and the seabed. The vertical stiffness of the flexible stretcher makes the floating structure a natural period of time for at least twenty seconds.

At least one preferred embodiment of the present invention represents a solution which makes it possible to obtain a combination of material usage, geometric and dimensional conformation and structural solutions which produces satisfactory technical solutions and low enough costs for the concept to be achieved. financially attractive.

In a preferred embodiment the concept is based on a long, thin, preferably cylindrical, long solution for the floating body of a floating wind turbine installation which, by its very nature, is designed to perform small amplitude of the waves. Another preferable precondition is that of a large displacement in relation to the weight of the turret and turbo. This is to achieve correct mass and weight distribution with respect to the required dynamic properties and stability.

According to the present invention, the high displacement and high strength required for structures immersed in deep areas can be obtained in a simple and economical manner by the use of concrete in a cylindrical underwater part. 0beton is a cheap material. Through systematization and organization of construction methods for serial production, labor costs can be very low.

Another important precondition for global costs is the need to avoid intensive work with expensive auxiliary vessels when individual turbines are installed at sea. This condition is obtained as the entire turbine can be towed to the installation site in the condition of fully assembled and anchored with a simple anchoring system. Installation and commissioning may be carried out in a protected building site and permanently installed. This condition is dependent on the existence of towing routes sufficient compromise between the construction site and the installation site. This is particularly the case with Norway and has so far been used for large concrete platforms. The present invention provides a wind turbine installation comprising: a floating body; a torredisposta on the floating body; a generator housing which is mounted on the tower, rotatable relative to the direction of the wind and equipped with a wind rotor; and an anchorage system which can be connected to anchors or anchorages on the seabed, characterized in that the wind turbine installation is designed so that: all the periods of the installation are outside the range of periods of waves rich in energy; the periods in pitch, T03, and transverse swing, T04, have a relationship such that T0s and / or T04 < 80% T03; and the relationship between T03 and T0s is not more than 0.5 or 1.

In another aspect, the present invention provides a method of designing a wind turbine installation, the installation comprising: a floating body; a torredisposta on the floating body; a generator housing which is mounted on the tower, rotatable relative to the direction of the wind and equipped with a wind rotor; and an anchorage system which can be connected to anchors or anchorage points on the seabed, the method comprising determining the dimensions and the weight distribution so that: all the periods of time for the installation are found outside the range of periods of energy-rich waves at the desired location for installation; the periods in pitch, T03, and in transverse swing, T04, have a ratio such that Tos and / or T04 < 80% T03; and the relationship between T03 and T0s is not more than 0.5 or 1. The present invention will hereinafter be described in more detail with reference to the drawings, in which: Fig. 1 shows the design of a turbine installation and Fig. 2 shows a simplified elevational view of a wind power plant with an alternate embodiment associated with the lowermost design of the floating body.

A floating wind power installation will, as shown in Fig. 1 and Fig. 2, consist of an anchored floating foundation or floating body 1 supporting a tall tower 2 with a wind turbine which is mounted on the top of the same tower , comprising a generator housing 3 enclosing an energy generating unit (not shown) and a rotor 4 arranged in connection with this unit. An important factor is that the floating foundation moves with the waves, which, in itself, is negative in relation to the operation of the turbine and the load on the tower. Another factor is that, given its limited stability, the turbine plant will also tilt laterally when subjected to the wind force.

Therefore, the main challenge in connection with the development of an installed floating turbine system is to minimize wave motion and achieve optimum stability while maintaining low bass. The cost is associated with the dimensions of the installation. Therefore, it will usually be a question of obtaining a concept with the minimum of material consumption. The best solution to minimize wave-induced movement and to obtain small dimensions is to use a deep, thin floating body which preferably consists of a cylindrical underwater body. The concept has two characteristic movements, pitch and longitudinal balance (transverse swing). Aarfagem is a purely vertical movement and the longitudinal balancer (transverse swing) is a derotation movement with a center of rotation located approximately in the center of gravity of the whole installation. The transverse balance and longitudinal balance are made in turn with their own orthogonal horizontal axes. To see great pitching and longitudinal swing movements it is important to make the proper periods out of the range in which the waves have a large amount of energy. In practice, this means that the periods themselves must be greater than values between 23 and 24 seconds for the two modes of movement. At the same time, the periods themselves must be sufficiently distant from one another to prevent movements from linking together. Good stability is required to obtain small lateral tilt angles for the turbine in operation. The stabilization effect is produced by moving the center of gravity. A large displacement and a low center of gravity produce large run-out forces, and therefore small angles of lateral tilt under load of wind. However, high stability produces a low longitudinal balance (transverse balance). In order to achieve maximum stability with a satisfactory longitudinal swing movement, the concept according to the present invention has been designed so that the longitudinal balance (transverse swing) operation seaches immediately above the range in which the waves have a large amount of energy, approximately between 25 and 26 seconds. In order to avoid a connection between the balance and longitudinal balance (transverse balance), the tightening period must be at a sufficient distance above the longitudinal balance (transverse balance) period, approximately between 30 and 31 seconds.

Another consideration is the dimensioning of the tower. In order to obtain the maximum resistance of the tower, it should have a large diameter at the bottom that passes through the surface of the water. The pitch period is the ratio of the displacement to the water plane area of the tower. Therefore, a specific displacement is required to achieve a pitch time of 30 seconds. Correct coordination between dimensions and ballast was obtained through a parameter study that included dimensioning calculations and dynamics analyzes.

Therefore, the installation of an offshore wind turbine must be designed in such a way that the requirements both for static properties and for dynamic properties are met. The requirements are associated, in particular, with the interaction between movement and vertical displacement (pitching) and rotation about a horizontal axis, horizontal balance (transverse balance). Based on the above, this is a summary of the requirements: The displacement (pgV) should be large enough to support the weight of the structure (Mg) plus the vertical forces coming from the anchor. 1. The system must have a sufficient static stability (initial stability and area under the &quot; GZ curve &quot;). 2. Static trim The maximum wind load on the wind turbine should be less than a specified value, cps_max / · and should be as low as possible, preferably less than 8o. 3. All proper periods should be outside the range of periods of energy-rich waves. 4. Tightening periods, T03, and longitudinal balance, T0s (transverse balance T04) shall be sufficiently distant from each other. 5. The ratio T03 / T05 should be different from values between 0,5 and 1,0 and a good distance from this range of values. Otherwise, the result could be the parametric excitation of the resonance motions.

It should generally be assumed that requirements 1 and 2 are satisfied. The static basis based on requirement 3 above is approximately given by:

It is assumed here that the floating body is a vertical column-shaped structure having a depth much greater than its width, and is the vertical coordinate of the rotor axis. Zm is the vertex coordinate of the anchor points. This point will be located close to the center of gravity of the system, which has the vertical coordinate zG. zB is the vertical coordinate of the deflutability center. V is the volume displacement of the floating bodies, p is the density of water and g is the graviational acceleration. The requirement 3 will now mean that we must have a sufficiently large displacement combined with a large GB = (ZB - zG). The proper longitudinal balance sheet (equiva- lent transverse balance) is approximately given by:

155 and A55 are the mass moment of inertia of hydrodynamic inertia, respectively, in the axis of dynamic rotation of the system. This is close to ten. More accurate values are obtained by considering the connected yaw / longitudinal balance movement. Equations [1] and [2] show that high stiffness, C55, contributes to keeping the lateral slope angle low, but, at the same time, the proper longitudinal balance period will be reduced as C55 increases. Therefore, it is necessary to try to cause I55 + A55 to remain sufficiently high to avoid T05 going into conflict with the wave periods. This can be achieved by making a deep, thin crust, as previously indicated. The proper pitch period is approximately given by:

Wherein C33 = pAWLg. AWL is the waterline area.

In addition, there is the effect of the vertical stiffness of the anchorages. M is the mass of the floating body. For a long, thin floating body, A3333 M. This shows that a high pitch period is achieved when there is a large displacement and a small area of water line.

From what has been said above it may be concluded that the requirements set forth in 4 and 5 hereinbefore mentioned may be combined if the displacement is sufficiently large. However, increased travel will increase costs. It is therefore necessary to find a combination of properties permitting simple hull umageometry, with sufficient displacement to meet the requirements described.

If we return to equation [1] and start from the idea that the wind turbine rotor diameter is 100 m, for example, and that GB is of the order of 10 m, it is possible to see that we need a shift of 100 times the urge?? static winding from the wind turbine if the static winding is to be kept below 0.1 radians (5.7 degrees). Therefore, with a turbine of 5 MW, we need a displacement of the order of values between 6,000 and 8,000 tons.

With the specified offset, the pitch period itself will be controlled by the waterline area. It was decided to make this period close to 30 seconds.

This makes it possible to situate the proper longitudinal packing period between the wave periods and the actual pitch period. (For Norwegian sea areas, the typical wave period range is from about 4 seconds to about 20 seconds). Accordingly, the previously mentioned requirements 4 and 5 are satisfied and the static adhere requirement is satisfied. In order to be able to position its own longitudinal balance within the range of values from 22 to 28 seconds and also to have a sufficient static stability, the purpose may be to have a large value GB, while I55 + A55 has a sufficiently low value , ensuring that 22 seconds &lt; T0s &lt; 28 seconds. This can be achieved by placing the ballast 7 slightly below the center of flow of the floating body. The ballast should be placed so that the requirements for the location of the center of gravity and for the moment of inertia are combined.

On the basis of what has been previously said, it is particularly convenient to produce the floating body, in the form of a cylindrical, elongated, thin body, inlet, and to make the tower in the form of a preferably cylindrical steel body. The floating body may conveniently have a drawn length of between 100 and 150 m. The displacement of the floating body can be reduced by introducing a &quot; lip &quot; or radial projection 6 at the base of the floating body, as shown in Fig. 2. This lip 6 may be designed so that the diameter of the base plate is greater than the deformable diameter of the floating body. Such a lip will have the following effect on the dynamic properties: • With respect to a vertical column, the bulging period will increase as a result of increasing the hydrodynamic mass in a vertical direction. Alternatively, the same pitch can be achieved with reduced displacement. • It is possible to maintain a low center of gravity, even if the moment of inertia in lateral swing (transverse swing) increases. This results in the freedom to give the proper period in the longitudinal balance (transverse balance) a convenient value and maintain the static properties.

Claims (11)

Wind turbine installation comprising: a floating body (1); a tower (2) disposed on the floating body; a generator housing (3) which is mounted on the tower, which is rotatable relative to the direction of the winding and is provided with a wind turbine (4); and an anchorage system (5) which can be connected to anchors or anchorages at the seabed, characterized in that the wind turbine system is designed so that: all periods of the installation are outside the range of periods of energy-rich waves; T0s and / or T0s, and / or in transverse balance, T04, have a relationship such that T0s and / or T04 < 80% T03; and the relationship between T03 and T0s is not close to 0.5 or 1. A wind turbine installation according to claim 1, wherein the static embedding, (max) installation under maximum wind load on the wind turbine is less than 8 degrees. A wind turbine installation according to claim 1 or 2, wherein the installation is designed, given dimensions and weight distribution, so that the proper longitudinal balance period lies within the range of values comprised between 22 and 28, and the corresponding period of time spent in the harvester is within the range of 30 to 35 seconds. Wind turbine installation according to claim 1, 2 or 3, wherein the floating body (1) consists of a thin and elongated concrete structure and the tower (2) consists of a steel structure. A wind turbine installation according to claim 4, wherein the thin and stretched concrete structure is cylindrical. Wind turbine installation according to claim 4 or 5, wherein the steel structure is cylindrical. A wind turbine installation according to any one of the preceding claims, wherein the floating body (1) is equipped at its lower end with a radial projection or lip (6) extending beyond the circumference of the upper part of the flowing body. A wind turbine installation according to any one of the preceding claims, wherein the floating body has a value between 100 and 150 m in length. A method of designing a wind turbine installation, the plant comprising: a floating body (1); a tower (2) disposed on the floating body; a generator housing (3) mounted on the tower, rotatable relative to the wind direction and equipped with a wind turbine (4); and an anchor mooring system (5) which can be attached to anchors or anchoring points on the seabed, the method comprising determining the dimensions and the weight distribution so that: all the periods for the installation are comprised of a range of periods of energy-rich waves at the desired site for installation; T03 and T05, and / or in transverse balance, T04, have a ratio such that T05 and / or T04 < 80% T03; and the relationship between T03 and T0s is not close to 0.5 or 1. A method according to claim 9, wherein the plant is designed so that the static banding, φ3 max of the installation under maximum wind load on the wind turbine is less than 8 degrees. The method according to claim 9 or 10, wherein the plant is designed in terms of size and weight distribution so that the longitudinally-balancing period itself lies within the range of values 22 to 28 seconds and the corresponding pitch period is within the range of 30-35 seconds.